This is the UK400 Club Rare Bird Alert highlighting all records of avian interest and published in association with Rare Bird Alert Pagers and utilising additional information gleaned from the Regional Birdlines, BirdGuides, local email groups and individual observers

Friday, 2 April 2010

I spend much of every fall and early winter going over photos of hummingbirds, hoping to find a vagrant among them, which I can then drive out to band. I say this just to comment that ID by photo is something that is considerably different from ID in the field. Much can be hidden, or misrepresented in photos. In the photos of the apparent Canvasback, I see a narrow sliver at the base of the bill which appears only to be on the bird's left side, but not even in every photo. So, the photos do not assure me that this is a real marking, rather than just some stray reflection or other photographic effect. Shouldn't it appear in every photo of the bird's left side?

In any case, here along the Detroit River, we get a chance to view 5-10% of the world population of Canvasbacks every fall and winter (my all-time peak count has been 28,000). I confess I don't look at them all, but do look at them a lot. I have never seen anything except a completely black bill on Canvasbacks here. I have not seen a marking such as is apparent in only one of the British photos. I don't know if this helps any, but this is my perspective from someone who sees so many Canvasbacks each year that they're often ignored in pursuit of other species.

For the second year running, this drake CANVASBACK has returned to Suffolk, in East Anglia (Britain). In every sense of the word, this is a typical drake Canvasback but my main reservation is the amount of pale bluish-white half-mooning on the upper surface of the upper mandible. I have always considered this feature to be associated with in-breeding and therefore suggesting that the bird is an escape; obviously in its ancestry, there are Northern Pochard genes.

However, I am keen to hear from birders in North America with experience of wild Canvasbacks. Do you see wild birds with this same feature and if so, what proportion of birds have this feature

Of the 5 or so Canvasbacks I have seen in Europe, four of them have shown some paling on the upper bill, suggesting this may well be a frequent feature. However, on the other hand, it could suggest that the majority of our birds are escapes

About Me

I have been birding since 1969 but became obsessed with 'twitching' in 1974 and haven't looked back since. Have driven over 1.3 million miles in pursuit of rare birds in the UK, where to date I have recorded 588 species in Britain and Ireland. I also have a fascination for the Birds of the Western Palearctic, where I have currently recorded 880 of the 1,064 species ever recorded. I am widely travelled in North America, as well as in Africa and Asia, and have written at least 29 books on my chosen subject, including best-sellers ''Ultimate Site Guide to Scarcer British Birds' and 'Rare Birds in Britain 1800-1990'. Established the UK400 Club in 1981 to cater for the most obsessive of the British birding fraternity and now concentrate on online publishing, via the www.uk400clubonline.co.uk website. Record Birding achievements include recording 386 species in Britain & Ireland in 1996 and 627+ in the Western Palearctic in 2008